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Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate

The main objective of this study is to demonstrate the performance characteristics of the Magic Plate (MP) system when operated upstream of the patient in transmission mode (MPTM). The MPTM is an essential component of a real‐time QA system designed for operation during radiotherapy treatment. Of pa...

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Autores principales: Alrowaili, Ziyad A., Lerch, Michael L.F., Petasecca, Marco, Carolan, Martin G., Metcalfe, Peter E., Rosenfeld, Anatoly B.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874939/
https://www.ncbi.nlm.nih.gov/pubmed/27074475
http://dx.doi.org/10.1120/jacmp.v17i2.5932
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author Alrowaili, Ziyad A.
Lerch, Michael L.F.
Petasecca, Marco
Carolan, Martin G.
Metcalfe, Peter E.
Rosenfeld, Anatoly B.
author_facet Alrowaili, Ziyad A.
Lerch, Michael L.F.
Petasecca, Marco
Carolan, Martin G.
Metcalfe, Peter E.
Rosenfeld, Anatoly B.
author_sort Alrowaili, Ziyad A.
collection PubMed
description The main objective of this study is to demonstrate the performance characteristics of the Magic Plate (MP) system when operated upstream of the patient in transmission mode (MPTM). The MPTM is an essential component of a real‐time QA system designed for operation during radiotherapy treatment. Of particular interest is a quantitative study into the influence of the MP on the radiation beam quality at several field sizes and linear accelerator potential differences. The impact is measured through beam perturbation effects such as changes in the skin dose and/or percentage depth dose (PDD) (both in and out of field). The MP was placed in the block tray of a Varian linac head operated at 6, 10 and 18 MV beam energy. To optimize the MPTM operational setup, two conditions were investigated and each setup was compared to the case where no MP is positioned in place (i.e., open field): (i) MPTM alone and (ii) MPTM with a thin passive contamination electron filter. The in‐field and out‐of‐field surface doses of a solid water phantom were investigated for both setups using a Markus plane parallel (Model N23343) and Attix parallel‐plate, MRI model 449 ionization chambers. In addition, the effect on the 2D dose distribution measured by the Delta(4) QA system was also investigated. The transmission factor for both of these MPTM setups in the central axis was also investigated using a Farmer ionization chamber (Model 2571A) and an Attix ionization chamber. Measurements were performed for different irradiation field sizes of [Formula: see text] and [Formula: see text]. The change in the surface dose relative to [Formula: see text] was measured to be less than 0.5% for the 6 MV, 10 MV, and 18 MV energy beams. Transmission factors measured for both set ups (i & ii above) with 6 MV, 10 MV, and 18 MV at a depth of [Formula: see text] and a depth of 10 cm were all within 1.6% of open field. The impact of both the bare MPTM and the MPTM with 1 mm buildup on 3D dose distribution in comparison to the open field investigated using the Delta(4) system and both the MPTM versions passed standard clinical gamma analysis criteria. Two MPTM operational setups were studied and presented in this article. The results indicate that both versions may be suitable for the new real‐time megavoltage photon treatment delivery QA system under development. However, the bare MPTM appears to be slightly better suited of the two MP versions, as it minimally perturbs the radiation field and does not lead to any significant increase in skin dose to the patient. PACS number(s): 87.50.up, 87.53.Bn, 87.55.N, 87.55.Qr, 87.56.Fc.
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spelling pubmed-58749392018-04-02 Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate Alrowaili, Ziyad A. Lerch, Michael L.F. Petasecca, Marco Carolan, Martin G. Metcalfe, Peter E. Rosenfeld, Anatoly B. J Appl Clin Med Phys Radiation Oncology Physics The main objective of this study is to demonstrate the performance characteristics of the Magic Plate (MP) system when operated upstream of the patient in transmission mode (MPTM). The MPTM is an essential component of a real‐time QA system designed for operation during radiotherapy treatment. Of particular interest is a quantitative study into the influence of the MP on the radiation beam quality at several field sizes and linear accelerator potential differences. The impact is measured through beam perturbation effects such as changes in the skin dose and/or percentage depth dose (PDD) (both in and out of field). The MP was placed in the block tray of a Varian linac head operated at 6, 10 and 18 MV beam energy. To optimize the MPTM operational setup, two conditions were investigated and each setup was compared to the case where no MP is positioned in place (i.e., open field): (i) MPTM alone and (ii) MPTM with a thin passive contamination electron filter. The in‐field and out‐of‐field surface doses of a solid water phantom were investigated for both setups using a Markus plane parallel (Model N23343) and Attix parallel‐plate, MRI model 449 ionization chambers. In addition, the effect on the 2D dose distribution measured by the Delta(4) QA system was also investigated. The transmission factor for both of these MPTM setups in the central axis was also investigated using a Farmer ionization chamber (Model 2571A) and an Attix ionization chamber. Measurements were performed for different irradiation field sizes of [Formula: see text] and [Formula: see text]. The change in the surface dose relative to [Formula: see text] was measured to be less than 0.5% for the 6 MV, 10 MV, and 18 MV energy beams. Transmission factors measured for both set ups (i & ii above) with 6 MV, 10 MV, and 18 MV at a depth of [Formula: see text] and a depth of 10 cm were all within 1.6% of open field. The impact of both the bare MPTM and the MPTM with 1 mm buildup on 3D dose distribution in comparison to the open field investigated using the Delta(4) system and both the MPTM versions passed standard clinical gamma analysis criteria. Two MPTM operational setups were studied and presented in this article. The results indicate that both versions may be suitable for the new real‐time megavoltage photon treatment delivery QA system under development. However, the bare MPTM appears to be slightly better suited of the two MP versions, as it minimally perturbs the radiation field and does not lead to any significant increase in skin dose to the patient. PACS number(s): 87.50.up, 87.53.Bn, 87.55.N, 87.55.Qr, 87.56.Fc. John Wiley and Sons Inc. 2016-03-08 /pmc/articles/PMC5874939/ /pubmed/27074475 http://dx.doi.org/10.1120/jacmp.v17i2.5932 Text en © 2016 The Authors. This is an open access article under the terms of the http://creativecommons.org/licenses/by/3.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Radiation Oncology Physics
Alrowaili, Ziyad A.
Lerch, Michael L.F.
Petasecca, Marco
Carolan, Martin G.
Metcalfe, Peter E.
Rosenfeld, Anatoly B.
Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate
title Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate
title_full Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate
title_fullStr Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate
title_full_unstemmed Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate
title_short Beam perturbation characteristics of a 2D transmission silicon diode array, Magic Plate
title_sort beam perturbation characteristics of a 2d transmission silicon diode array, magic plate
topic Radiation Oncology Physics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874939/
https://www.ncbi.nlm.nih.gov/pubmed/27074475
http://dx.doi.org/10.1120/jacmp.v17i2.5932
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